MOLTEN FUEL REACTOR THERMAL MANAGEMENT CONFIGURATIONS
Configurations of molten fuel salt reactors are described that allow for active cooling of the containment vessel of the reactor by the primary coolant. Furthermore, naturally circulating reactor configurations are described in which the reactor cores are substantially frustum-shaped so that the thermal center of the reactor core is below the outlet of the primary heat exchangers. Heat exchanger configurations are described in which welded components are distanced from the reactor core to reduce the damage caused by neutron flux from the reactor. Radial loop reactor configurations are also described.
1 . A method for actively cooling a containment vessel and fuel salt in a molten fuel salt nuclear reactor comprising:
flowing primary coolant into the containment vessel adjacent to a first portion of the containment vessel, thereby cooling the first portion;
flowing primary coolant into a heat exchanger within and spaced apart from the containment vessel, the heat exchanger discharging cooled fuel salt;
routing discharged cooled fuel salt through a channel adjacent to a second portion of the containment vessel, thereby cooling the second portion;
routing cooled fuel salt through the channel adjacent to a neutron reflector, thereby cooling the neutron reflector; and
wherein the cooled neutron reflector is adjacent to a third portion of the containment vessel such that cooling the neutron reflector indirectly cools the third portion.
2 . The method of claim 1 wherein the flowing the primary coolant into the containment vessel further comprises:
flowing the coolant through a coolant inlet duct inside the containment vessel thermally connected to the first portion of the containment vessel.
3 . The method of claims 1 wherein the flowing the primary coolant into the containment vessel further comprises:
flowing the coolant through a coolant inlet duct inside the containment vessel to a heat exchanger coolant inlet adjacent a heat exchanger cooled fuel salt outlet.
4 . The method of claim 1 wherein the flowing the primary coolant into the containment vessel further comprises:
flowing the coolant through a coolant inlet duct inside the containment vessel thermally connected to the first portion of the containment vessel.
5 . The method of claim 1 wherein the fuel salt is a mixture of at least one fissile salt and at least one non-fissile salt.
6 . The method of claim 1 wherein the fuel salt includes one or more of the following fissile salts: UF 6 , UF 4 , UF 3 , ThCl 4 , UBr 3 , UBr 4 , PuCl 3 , UCl 4 , UCl 3 , UCl 3 F, and UCl 2 F 2 .
7 . The method of claim 1 wherein the fuel salt includes one or more of the following non-fissile salts: NaCl, MgCl 2 , CaCl 2 , BaCl 2 , KCl , SrCl 2 , VCl 3 , CrCl 3 , TiCl 4 , ZrCl 4 , ThCl 4 , AcCl 3 , NpCl 4 , AmCl 3 , LaCl 3 , CeCl 3 , PrCl 3 and/or NdCl 3 .
8 . The method of claim 1 wherein the fuel salt is a mixture of UCl 4 , UCl 3 , and one or both of NaCl and MgCl 2 .
9 . A molten fuel nuclear reactor comprising:
an upper neutron reflector defining a top of a reactor core;
a lower neutron reflector defining a bottom of the reactor core;
at least one inner neutron reflector defining sides of the reactor core;
at least one heat exchanger that receives heated fuel salt at a heat exchanger fuel salt inlet below a reactor core heated fuel salt outlet, transfers heat from the fuel salt to a coolant, and discharges the cooled fuel salt at a heat exchanger fuel salt outlet fluidly connected to a reactor core cooled fuel salt inlet;
the at least one heat exchanger including a welded component separated from the fuel salt by one of the upper neutron reflector, the lower neutron reflector, the inner neutron reflector or a neutron moderator.
10 . The molten fuel nuclear reactor of claim 9 wherein the welded component is a tube sheet.
11 . The molten fuel nuclear reactor of claim 10 wherein the welded component is a tube sheet through which the coolant exits the at least one heat exchanger and the tube sheet is separated from the fuel salt by the upper neutron reflector.
12 . The molten fuel nuclear reactor of claim 10 wherein the welded component is a tube sheet through which the coolant enters the at least one heat exchanger and the tube sheet is separated from the fuel salt by the lower neutron reflector.
13 . The molten fuel nuclear reactor of claim 10 wherein the welded component is a tube sheet through which the coolant both enters and exits the at least one heat exchanger.
14 . The molten fuel nuclear reactor of claim 13 wherein the tube sheet through which the coolant both enters and exits the at least one heat exchanger is located above the reactor core.
15 . The molten fuel nuclear reactor of claim 13 wherein the tube sheet through which the coolant both enters and exits the at least one heat exchanger is separated from the fuel salt by the upper neutron reflector.
16 . The molten fuel nuclear reactor of claim 13 wherein the tube sheet through which the coolant both enters and exits the at least one heat exchanger is separated from the fuel salt by a neutron absorber.
17 . A radial loop molten salt reactor comprising:
a reactor core containment vessel;
one or more reflectors in the reactor core containment vessels, the one or more reflectors defining a reactor core volume within the reactor core containment vessel; and
a plurality of heat exchanger legs spaced apart outside of the reactor core containment vessel, each heat exchanger leg having a reactor outlet pipe configured to receive heated fuel salt from the reactor core volume, a heat exchanger that transfers heat from the heated fuel salt to a primary coolant thereby creating a cooled fuel salt, and a reactor inlet pipe configured to return the cooled fuel salt into the reactor core volume.
18 . The radial loop molten salt reactor of claim 17 further comprising:
a secondary containment vessel containing the reactor core containment vessel and the plurality of heat exchanger legs, the secondary containment vessel defining a volume sufficient to hold at least all of the fuel salt contained in reactor core containment vessel and in the plurality of heat exchanger legs.
19 . A molten salt nuclear reactor comprising:
a substantially frustum-shaped reactor core containing a fissionable fuel salt, the reactor core having a heated fuel salt outlet, a cooled fuel salt inlet, and a thermal center above the cooled fuel salt inlet;
at least one heat exchanger that receives heated fuel salt at a heat exchanger fuel salt inlet below the reactor core's heated fuel salt outlet, transfers heat from the fuel salt to a coolant, and discharges the cooled fuel salt at a heat exchanger fuel salt outlet fluidly connected to the reactor core's cooled fuel salt inlet; and
wherein the thermal center of the reactor core is at a level below the heat exchanger fuel salt outlet; and
wherein the location of the thermal center causes natural circulation in the case of a loss of forced flow while the reactor is in a state of criticality.
20 . The molten salt nuclear reactor of claim 19 wherein the reactor core has a depth that is the distance between the top level of the fuel salt in the reactor core and the bottom of the fuel salt in the reactor core, the reactor further comprising:
wherein a ratio of a distance below the heat exchanger fuel salt outlet of the thermal center to the depth of the reactor core of the thermal center is between 0.1 and 0.45; and
wherein the shape of the reactor core is selected from a frustum of a cone, a frustum of a pyramid, a trapezoidal prism or a hyperboloid.